Step unit for a modular spiral staircase



FIG. 1 is a front elevational view of the step unit for a modular spiralstaircase of the present invention;

FIG. 2 is a back elevational view of the step unit for a modular spiralstaircase of FIG. 1;

FIG. 3 is a left side elevational view of the step unit for a modularspiral staircase of FIG. 1;

FIG. 4 is a right side elevational view of the step unit for a modularspiral staircase of FIG. 1;

FIG. 5 is a top plan view of the step unit for a modular spiralstaircase of FIG. 1;

FIG. 6 is a bottom plan view of the step unit for a modular spiralstaircase of FIG. 1; and,

FIG. 7 is a front elevational in use view of the step unit for a modularspiral staircase of FIG. 1.

The broken lines disclosing a spiral staircase is for illustrativepurposes only, and forms no part of the claimed design.

The ornamental design for a modular spiral staircase, as shown and described. 